ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-7-4295-2007Sensitivity of PM<sub>2.5</sub> to climate in the Eastern US: a modeling case studyDawsonJ. P.12AdamsP. J.23PandisS. N.141Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, USA2Department of Engineering and Public Policy, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, USA3Department of Civil and Environmental Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213, USA4Department of Chemical Engineering, University of Patras, 26500, Patra, Greece2208200771642954309This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article is available from http://www.atmos-chem-phys.net/7/4295/2007/acp-7-4295-2007.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/4295/2007/acp-7-4295-2007.pdf

The individual effects of various meteorological parameters on PM<sub>2.5</sub>
concentrations in the Eastern US are examined using the PMCAMx chemical
transport model so that these effects and their relative magnitudes can be
better understood. A suite of perturbations in temperature, wind speed,
absolute humidity, mixing height, cloud cover, and precipitation are imposed
individually on base case conditions corresponding to periods in July 2001
and January 2002 in order to determine the sensitivities of PM<sub>2.5</sub>
concentrations and composition to these separate meteorological parameters.
Temperature had a major effect on average PM<sub>2.5</sub> in January (&minus;170 ng m<sup>&minus;3</sup> K<sup>&minus;1</sup>)
due largely to the evaporation of ammonium nitrate and
organic aerosol at higher temperatures; increases in sulfate production with
increased temperature counteracted much of this decrease in July. Changes in
mixing height also had major effects on PM<sub>2.5</sub> concentrations: 73 ng m<sup>&minus;3</sup>
(100 m)<sup>&minus;1</sup> in January and 210 ng m<sup>&minus;3</sup> (100 m)<sup>&minus;1</sup> in
July. Changes in wind speed (30 to 55 ng m<sup>&minus;3</sup> %<sup>&minus;1</sup>) and absolute
humidity (15 to 20 ng m<sup>&minus;3</sup> %<sup>&minus;1</sup>) also had appreciable effects on
average PM<sub>2.5</sub> concentrations. Precipitation changes had large impacts
on parts of the domain (a consequence of the base case meteorology), with
sensitivities to changing area of precipitation in July up to 100 ng m<sup>&minus;3</sup> %<sup>&minus;1</sup>.
Perturbations in cloud cover had the smallest effects
on average PM<sub>2.5</sub> concentrations. The changes in PM<sub>2.5</sub>
concentrations resulting from changing all eight meteorological parameters
simultaneously were approximately within 25% or so of the sum of the
changes to the eight individual perturbations. The sensitivities of
PM<sub>2.5</sub> concentrations to changes in these meteorological parameters
indicate that changes in climate could potentially have important impacts on
PM<sub>2.5</sub> concentrations.